Swing shift lift truck



Qua 6 19m MQMILLAN swme SHIFT LIFT TRUCK 4 Sh e ets-Sheet 1 Filed D60.4, 1968 INVENTOR.

Hclrry C. McMillan ATTORNEYS.

Oct. 6, 1970 H. c. M MILLAN SWING SHIFT LIFT TRUCK 4 Sheets-Sheet 2 IFiled Dec. 4, 1968 INVENTOR Harry C. McMillan wfl fiql ATTORNEYS.

Oct. 6, 1970 mc 3,532,238

SWING SHIFT LIFT TRUCK Filed Dec. 4, 1968 4 Sheets-Sheet 5 I INVENTOR.Harry C. McMillan ATTORNEYS.

H. C. M MILLAN SWING SHIFT LIFT TRUCK 4 Sheets-Sheet 4.

INVENTOR Harry C. McMillan BY ATTORNEYS.

.7 bal g 1 @W QQJQQ Q19 Oct. 6, 1970 Filed Dec. 4,, 1968 Y a L nitedStates Patent O 3,532,238 SWING SHIFT LIFT TRUCK Harry C. McMillan,Cherry Hill, N.J., assignor to Drexel Dynamics Corporation, Horsham,Pa., a corporation of Pennsylvania Filed Dec. 4, 1968, Ser. No. 781,149Int. Cl. B66f 9/10 US. Cl. 214-672 2 Claims ABSTRACT OF THE DISCLOSURE Aswing shift fork lift truck is disclosed having a lift assembly attachedto the side of a single swing arm. One end of the single swing arm ispivotally mounted on the vehicle chassis on a side shift mechanismhaving a transverse travel across the front of the vehicle. The vehicleis capable of operating either as a front loader by positioning the liftassembly immediately in front of the drive axle, or as a side loader byrotating the swing arm to move the lift assembly to a position parallelto the direction of the vehicle travel. The side shift mechanism is thenused to move the lift assembly transversely to enter or remove the forksfrom the load. The operator is seated on one side of the chassis in afixed position facing forward. All operator controls are located in theoperators compartment.

BACKGROUND OF THE INVENTION Fork lift trucks have been designed andconstructed in a wide variety of forms for a wide variety of purposes.

A principal object of the present invention is to design and construct avehicle of relatively simple design and construction which neverthelessprovides a high degree of maneuverability and which is capable, forexample, of picking up pallets in narrow aisles, or going deep for apallet load, or picking up a long load in a narrow aisle, or making aright angle turn at a relatively narrow intersection, and so forth.

In the prior art, fork lift vehicles having some degree of similarity tothe fork lift vehicle of the present application are shown in US. Pats.2,799,418 and 3,313,436.

In US. Pat. 2,799,418, the vehicle has a transversely movable carriageon which a mast is supported. However, the mast is fixed verticallyrelative to the cross carriage. Hence, to raise and lower the forks, theentire transverse carriage is moved up and down on the vehicle. Incontrast to Pat. 2,799,418, in the vehicle of the present application,the transversely movable carriage is vertically stationary and theload-carrying forks are moved up and down on the mast.

In US. Pat. 3,313,436, the vehicle has a mast assembly which ispivotally mounted, at its center point, on a king post carried on atransverse carriage. The carrier frame of the mast assembly is cutawayat the forward side to permit the carrier frame to be lowered to thegound level while straddling the carriage guide, front axle and frontwheel, and the frame of the lift truck is shaped to have a recess to therear of the front axle to admit the carrier frame. In contrast to theconstruction shown in US. Pat. 3,313,436, in the vehicle of the presentapplication, the carrier frame which supports the lift forks is notcutaway, and there is no recess to the rear of the front axle for thecarrier frame.

SUMMARY OF THE INVENTION In the vehicle of the present invention, themast or lift assembly is mounted on a single swing arm and one end ofthe swing arm is pivotally mounted on a king post which is carried on aslide carriage transversely movable across the front of the vehicle.

3,532,238 Patented Oct. 6, 19-70 FIG. 1 is a perspective view showing afork lift truck according to the present invention;

FIG. 2 is a plan view, partly cutaway, of the fork lift truck of FIG. 1;

FIG. 3 is an enlarged side elevational view of the lift truck of FIG. 1,looking along the line 3-3 of FIG. 1;

FIG. 4 is a detailed plan view looking down along the line 44 of FIG. 3;

FIG. 5 is an elevational view, in section, of the transverse carriagedrive mechanism looking along the line 5-5 of FIG. 4;

FIG. 6 is an elevational view looking along the line 6-6 of FIG. 4,showing the swing arm and the mast tilt mechanism.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring first to FIG. 1, thereis shown a fork lift vehicle embodying the present invention andcomprising a vehicle frame 12 having an operators control station 14,and a compartment 15 for the batteries which power the vehicle, andhaving a pair of front drive wheels 16, and a pair of steerable rearwheels 17.

Supported on the vehicle chassis or frame 12 at the forward end thereofis a mast or lift assembly including, among other things, fixed guiderails 21, a movable guide 22 slidable up and down in the fixed guidechannels 21, and a carrier frame 23 which is movable vertically relativeto both the fixed guide 21 and the movable guide 22 and which carriesthe lift fork 24. A pair of chains 25 are trained over pulleys (notshown) carried at the upper end of the piston of a hydraulic liftcylinder 26. One end of the chains 26 is fixed to the carrier frame 23.The other end is fixed to the fixed guide 21. Thus, when the liftcylinder 26 is extended, the carrier frame 23 is lifted through adistance twice that of the distance through which the piston is moved.The mast or lift assembly used in the vehicle of the present inventionis a known form of mast and need not be further described.

In accordance with the present invention, mounted for transversemovement across the forward end of the vehicle chassis is a crosshead 40having at its rearward end a tongue 41 which is received within thechannel of a fixed rear guideway 42 formed in the chassis 12. Sinceguideway 42 takes the upward thrust imposed by the weight of the load onthe fork 24, the guideway 42 also functions as a load bearing surfacefor the crosshead.

As shown in FIG. 3, the undersurface of the crosshead 40, at a locationjust above the front wheels 16, is provided with bearing plates 43 whichrest on a slide 44 which supports the crosshead during its transversetravel. Slide 44 is supported on a bearing block 45 and is guided in itstravel by a series of guide brackets 46 secured, as by welding, to thebearing block 45.

The bearing block 45 is provided with a center groove 45a which runs thelength of the block 45 and which receives the lower leg of an endlesschain 47 which is trained over a pair of rollers 48 and 49 supported onshafts carried by the slide 44, as best seen in FIG. 5. A groove 40a inthe underside of the crosshead 40 receives the upper leg of the endlesschain 47. The bearing plates 43 are on either side of the groove 40a.

A first pin 51 fixes the lower leg of endless chain 47 to the bearingblock 45, and a second pin 52 fixes the upper leg of the chain 47 to thecrosshead 40. It will be apparent that two separate chains may replacethe endless chain 47, with one end of each chain secured to the bearingblock 45 and the other end of each chain secured to the crosshead 40with one of the chains trained around one of the rollers 48 and theother chain trained around the other roller 49.

Slide 44 is moved by a hydraulic jack comprising a cylinder 53 andpiston rod 54, best seen in FIG. 4. One end of the cylinder 53 ispivotally secured to a bracket 55 fixed to the chassis 12. The end ofthe piston rod 54 is pivotally secured to a connecting arm 56 which issecured, as by welding, to the slide 44. Thus, when the piston rod 54 isextended or retracted to move the slide 44, the crosshead 40 is movedtransversely through a distance equal to twice that of the distancethrough which the slide 44 is moved.

crosshead 40 has a forwardly projecting portion 140 which carries avertically-disposed king post 60 supported for rotation in bearings atits upper and lower ends. Secured to king post 60 for rotation therewithis a swing arm assembly comprising upper and lower arms 61 and 62 havingwelded thereto the upper and lower faces of a tubular member 63. Tubularmember 63 extends outwardly transversely across the rear of the mastassembly, but the arms 61 and 62 terminate at, and are welded to, a sideplate 64 having therein an opening through which the tubular member 63passes. At the outward end of the tubular member 63 is an outer sideplate 65. Both side plates 64 and 65 are Welded to the tubular member63.

Secured, as by welding, to the outer faces of the side rails of thevertically-fixed mast guide 21 are bearing blocks 21a, and secured, asby welding, to the inside surfaces of the plates 64 and 65 and to thetubular member 63 are bearing blocks 77 and 78. Trunnions 75 and 76 arereceived within the bearing blocks and in this manner the mast tiltassembly is supported on the swing arm. A bronze bushing, such as 75a ofFIG. 6, may be interposed between the trunnions and the bearing blocks77 and 78.

Side plates 64 and 65 each have a rearwardly extending portion, andextending transversely between these rearward portions is a plate 66having brackets 67 and 68 (FIG. 4) for supporting the rearward end of apair of tilt cylinders 69 and 70. The piston rods 71 and 72 of the tiltcylinders are pivotally connected at their forward ends to a pair ofears 73 and 74 which are welded to the sides of the vertically-fixedmast guide 21.

The swing arm, including arms 61 and 62, tubular member 63, side plates64 and 65, and rear plate '66, is supported as a unit on the king post60. This swing arm unit is not tiltable. Thus, when tilt cylinders 69and are actuated to extend or retract the piston rods 71 and 72, thevertically-fixed mast guide 21 is pivotally moved about the trunnions 75and 7-6.

When the vertically fixed guide 21 is tilted, the vertically movableguide 22 also tilts since the channels of the guides are intermeshed.And, of course, the verticallymovable carrier frame 23 and forks 24 alsotilt.

It has just been described how the mast assembly (21, 22, 23, 24, 25,26) is supported on the swing or pivot arm assembly (61, 62, 63, 64, 65,'66, etc.) which in turn is supported in cantilever fashion on the kingpost 60 carried in the crosshead 40. The pivot arm assembly is movedpivotally about the axis of the king post 60 by a hydraulic jackcomprising the cylinder and piston rod 81. One end of the pivot cylinder80 is pivotally secured to a bracket 82 secured, as by welding, to theoutward side plate 65. The opposite end of the piston rod 81 ispivotally secured to a bracket 83 carried by the crosshead 40. Thus,when the pivot piston rod 81 is extended or retracted, the pivot armassembly is pivoted about the king post 60 in the manner indicated inFIG. 2.

In FIG. 2, the vehicle is illustrated in solid line with the fork 24extended forwardly. In this position of the fork 24, the crosshead '40and king post 60 are at the right side of the vehicle as indicated bythe solid line showing of the king post. If the pivot arm is pivotedclockwise when the crosshead or carriage 40 and king post '60 are at theright side of the vehicle, the mast assembly and fork 24 will move fromthe solid line position shown in FIG. 2 to the dot-and-dash positionindicated by the letter A. If the carriage 40 is then moved transverselyacross the front of the vehicle from the right limit position to theleft limit position, the mast assembly and forks 24 will move to thedot-and-dash lines identified by letters B1 through B5 indicates thepositions the mast assembly would assume if the pivot or swing arm unitwere to be moved counter-clockwise through 90 When the carriage 40 is atthe left side of the vehicle.

It will be seen that the present invention provides a mobileload-carrying lift vehicle characterized by a carriage mounted fortransverse movement across a forward end of said chassis, a king orpivot post carried by said carriage at a forward portion thereof andmounted for pivotal movement about a vertical axis, a swing arm unitmounted in cantilever fashion on said pivot post entirely to one sidethereof for pivotal movement in a generally horizontal plane about theaxis of said pivot post, and a tiltable mast lift assembly mounted onsaid swing arm and having vertically movable load-carrying forks orother platform. The vehicle is further characterized by means at therearward end of the transverse carriage for taking the upward thrustimposed thereat by the downward load on the swing arm unit. The meansjust referred to, in the illustrated form, consists of the carriage orcrosshead being given a tapered configuration toward the rear,terminating in a tongue which is received for sliding transversemovement within a cross channel in the chassis. This cross channel takesthe upward thrust generated by the downward thrust of the load on theswing arm.

In the vehicle of the present invention, in preferred form, the carriageis mounted on a transversely movable slide, and the slide is mounted ona transverse bearing block fixed to the chassis. A belt or chain isprovided having one point fixed to the chassis and another to thecarriage, and trained over rollers carried by said slide. A firsthydraulic jack is connected between the chassis and the slide for movingthe slide, thereby to move the carriage. A second hydraulic jack isconnected between the.

carriage and the swing arm for pivoting the swing arm about the kingpost. Hydraulic jacks are also provided for moving the forks vertically,and for tilting the mast.

While the preferred embodiment of this invention has been described insome detail, it will be obvious to one skilled in the art that variousmodifications may be made without departing from the invention ashereinafter claimed.

What is claimed is:

1. A lift vehicle comprising:

(a) a mobile chassis;

(b) a carriage mounted for transverse movement across a forward endportion of said chassis;

(c) a pivot post carried by said carriage at a forward portion thereofand mounted for pivotal movement about a vertical axis;

(d) a swing arm mounted in cantilever fashion on said pivot post and toone side thereof for pivotal movement in a generally horizontal planeabout the post axis of said pivot post;

(e) a mast lift assembly mounted on said swing arm and havingload-carrying members;

(f) means at the rearward end of the transverse carriage for taking theupward thrust imposed thereat by the downward load on the swing arm, therearward portion of said carriage being tapered to form a tongue, saidmeans for taking the upward thrust comprises a cross load-bearingchannel in said chassis receiving said tongue;

(g) means for moving the carriage transversely across the chassis;

(h) means for pivoting the swing arm;

(i) means for raising and lowering the load-carrying members of the mastlift assembly;

(j) means mounting said carriage on a transversely movable slide;

(k) said slide being mounted on a transverse bearing block fixed to saidchassis;

(l) flexible link means fixed to said chassis and to said carriage andcarried by said slide;

(m) means connected between said chassis and said slide for moving saidslide;

(n) said swing arm includes an upper and lower plate fixed to said kingpost;

(0) an elongated tubular member secured to said upper and lower platesand extending outwardly from the king post;

(p) a pair of side plates, one secured to the outward end of saidtubular member and the other substantially inward thereof secured tosaid upper and lower plates and having an opening through which saidtubular member passes;

(q) means, including trunnions, for pivotally mounting said mast liftassembly on said inward and outward side plates.

2. A lift vehicle according to claim 1 characterized in that a pair ofhydraulic jacks are connected between said swing arm and said mast liftassembly for tilting said mast lift assembly.

References Cited UNITED STATES PATENTS FOREIGN PATENTS 7/1958 Germany.1/ 1964 Great Britain.

GERALD M. FORLENZA, Primary Examiner R. B. JOHNSON, Assistant ExaminerUS. Cl. X.R.

